Currently, a semiconductor device having nonvolatile memory cells, such as an EEPROM (Electrically Erasable and Programmable ROM) or a flash memory, is generally used in diverse fields. The number of rewrites thereon, improvement of reliability such as data retention tolerance, and miniaturization of the structure are important subjects. On the other hand, a flash memory that is represented as a floating type that is in the marketplace has recently attracted attention since it is said that a resistance change nonvolatile memory device has a high reliability in addition to a simple structure, a high-speed rewrite function, and multi-value technology, and is suitable for high performance and high integration.
Since a nonvolatile memory device including a phase change RAM (PRAM) has a structure in which a resistance change layer that functions as a memory portion is arranged between two electrodes, the memory structure is simple, and easy miniaturization is possible. The phase change memory device is a nonvolatile memory device that is operated as a memory device using the fact that a phase change material that forms a resistance change layer has different electrical resistances of several orders depending on whether the phase change material is in an amorphous state or in a crystal state (for example, see JP-A-2007-134676). Further, there is a nonvolatile memory device that stores data using a colossal electro-resistance effect (CER effect) of a material that forms a resistance change layer (for example, see JP-A-2003-068983). Further, there is a nonvolatile memory device in which a resistance change layer is formed from an ionic conductor that includes a metal (for example, see JP-A-2005-166976 and JP-A-2005-197634). Further, as a kind of nonvolatile memory device, a PMC (Programmable Metallization Cell) is known (for example, see JP-A-2005-322942).
However, in order to achieve a large capacity of a nonvolatile memory device through the leading semiconductor process, low voltage and low current are highly necessary. This is because as the drive transistor is miniaturized, its drive current and voltage become lowered. That is, in order to realize a miniaturized nonvolatile memory device, it is necessary that the nonvolatile memory device has a performance capable of being driven by miniaturized transistors. Further, in order to perform low-current driving, a low-current and high-speed (short pulse in the nanosecond order) write/read performance becomes necessary.